[Elecraft] OT - sound cards

[David Gilbert]

If you can't even make decent quality voice recordings, you have 
something else wrong.  Unless it is simply defective, even the cheapest 
sound chip out there isn't going to act like you describe.

And what exactly do you think the I/Q outputs of the KX3 are going to be 
using?

Dave   AB7E



On 1/8/2012 11:24 PM, Erik Basilier wrote:
> I have never expected standard sound cards to be really good, but I have
> nevertheless used them successfully for purposes like digital modes. When I
> built a SoftRock I got an E-MU 0202 for the higher sampling frequency. When
> I sold my LP-PAN and SoftRock, the E-MU went with them. My current main
> computer is a high-end HP desktop running Windows 7, a little over a year
> old. The output sound quality is not bad, but not until recently did I use
> the microphone input for anything. Then I suddenly needed to make some voice
> recordings using a microphone. Every recording has terrible background noise
> which is not being picked up by the mike, an has nothing to do with
> grounding etc. The noise is a mix of white (or is it pink?) noise with added
> irregular frying-pan crackle and some mosquito whine. It is the same with
> different microphones, and increased microphone output doesn't help because
> the noise is not reduced when the software mike gain is reduced. Overall,
> the S/N is worse than for the average landline telephone call (but of course
> the latter at times has distortion that is much worse than the computer's).
> Curious, I took the same microphones to my old XP laptop. It had much less
> noise! To perfect the comparison I then went to adjust the mike gain in the
> XP software. Hmmm. there is a checkmark in a box for noise reduction. I
> unchecked it, and now the laptop had a lot of noise, but not quite as much
> as the desktop. Then I went to the desktop to look for a noise reduction
> option. I found it and turned it on. Big improvement. Now the noise is low
> enough for my voice recording purposes. However, the noise reduction causes
> very obvious artifacts similar to ones often found in HAM radio noise
> reduction. The noise reduction on the old laptop seemed better in this
> respect.
>
>
>
> At this point I obviously don't know everything that is going on, but I have
> seen enough to have a gut feel. So, I will lay out my thoughts to the group,
> and hope that others will fill in the blanks and correct me where I may be
> jumping to conclusions. Here are my current thoughts:
>
>
>
> .         It is somewhat difficult to keep noise out of a low-level audio
> circuit that is sitting next to a lot of high-speed digital circuitry, as on
> a PC motherboard (there is no separate sound card in this PC).
>
> .         Rather than spend the extra bucks for physical separation or
> shielding, etc, PC manufacturers routinely ignore the noise issues, and
> cover them up with noise reduction algorithms, which get more aggressive as
> the noise environment inside PC's gets worse.
>
> .         Other brands of computers are probably just as bad (or can someone
> recommend a brand that comes with low noise audio as standard?).
>
> .         If I get another external USB sound card of good quality, I should
> definitely not limit its use to soundcard-dependent SDR's, but use it for
> digital modes too.
>
> .         If I do use an internal soundcard for digital modes again, I had
> better make sure that the noise reduction in the PC is turned off, as noise
> reduction is known to be incompatible with digital modulation schemes.
>
> .         As if I didn't know it already, Elecraft has it right when they
> don't make their radios rely on computer sound cards!
>
>
>
> 73 And thanks in advance,
>
> Erik K7TV
>
>
>
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